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RE: bouncy existing floor joists

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John-
 
Great idea! Glad you're not really retired!
 
As an alternative, what about 7/16" plywood, oops, I mean Wood Structural Panels ? I don't think the discontinuity provided by the gaps in the panels is a large issue since you're just trying to improve the moment of interia, actually, the M/EI area diagram. Of course, the additional DL might be an issue.
 
Just a thought.
 
Regards,
 
T. William (Bill) Allen, S.E. (CA #2607)
V/F (949) 248-8588
San Juan Capistrano, CA
-----Original Message-----
From: John Rose [mailto:jrose36(--nospam--at)earthlink.net]
Sent: Friday, June 27, 2003 9:31 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: bouncy existing floor joists

If you can access the underside of the floor joists, one of the most effective ways to stiffen floor joists is to add (nail and glue with elastomeric construction adhesive) a 1x4 or 2x4 flatwise to the bottom of each joist, to create an upside down T-beam.  It adds a lot of stiffness to the floor.  It would be preferable to make the added pieces continuous between supports, but even if there was a butt joint or two (in low moment regions), it would still stiffen the floor a lot.
 
John Rose
APA-Retired
Tacoma, WA
 
 
----- Original Message -----
From: D.A.
Sent: 6/27/2003 8:10:55 PM
Subject: bouncy existing floor joists

HI
 
I have A problem A custom home built in 1980's with 2x10 floor joist  at 12" on center
it spans 18 feet long the floor has 1 1/2" light weight concrete
the owner try to remodel and want to stiffen  the floor system because is very bouncy
and vibrating even it has dry wall at bottom
so the dry wall pulled off and just added 1 3/4 x 91/4 PSL 2.0 E. at 12' on center .
no dry wall added yet and the floor still bouncy and vibrating
1- is it possible after adding the dry wall will be ok
2- what other solution can be done without adding beams or increase the depth of floor joists
    because adding a beam will be deeper and too big due to long span where possible to
    add post.
3- is it adding steel tube joist at 24" will solve the problem
 
thank in advance for any advice
Dave A. P.E.  
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